1. Field of the Invention
This invention relates to cable transmission systems.
More particularly, the present invention relates to connectors of the type normally used to connect coaxial cables to equipment in environmentally sealed housings.
In a further and more specific aspect, the instant invention concerns coaxial cable connectors having improved insulators for preventing corrosion of the central conductor pins when moisture accumulates in the equipment housing.
2. Prior Art
The use of coaxial cable to transmit signals from a primary source, such as a central computer or an antenna, to a number of receivers such as computer terminals or television sets, is generally well known. In addition, coaxial cable may be used to couple the source and receivers to any number of intermediate auxiliary devices such as amplifiers, extenders and directional taps.
Most equipment used in conjunction with coaxial cable is contained within environmentally sealed housings having entry ports of standard dimensions. Typically, the cable is coupled to the housing by a connector having a tubular outer body which is configured to be matingly received in the entry port. The outer body of the connector encircles a central conductor pin which extends into a terminal within the housing to make an electrical connection with the equipment. The conductor pin is separated from the outer body by a non-compliant cylindrical dielectric, the distal end of which is conventionally recessed with respect to the distal end of the outer body.
In spite of the fact that most equipment housings are initially environmentally sealed, circumstances do arise in which it is necessary to open the housings and in which moisture is allowed to enter. This is particularly true of outdoor equipment which must be opened for repair during rain or snow storms. In addition, seals may become damaged after some period of time, or technicians may neglect to completely close the housing after troubleshooting or repair. As a result, equipment housings are frequently not as dry in practice as they should be in theory.
Moisture within the equipment housing causes gradual, generalized corrosion of the metallic parts of the connector and may eventually lead to complete failure of the connector. In addition to this generalized corrosion, more rapid, highly selective corrosion has been observed to occur at the base of the central conductor pin and along the inner circumference of the distal end of the outer body. Corrosion of the pin causes the pin to break into two pieces, causing an open circuit and completely stopping operations in the cable system. In some cases, complete failure of the pin will take place in as little as one month.
This extremely selective corrosion of the conductor pin has long puzzled connector designers, who have been unable to understand the failure mechanism behind such corrosion and to prevent it from occurring. It has now been determined, however, that the primary cause of corrosion is moisture in the recessed area between the pin and the body of the connector, both of which are made of metal. Any condensate or other droplet of liquid which flows down the interior sides of the equipment housing and onto the recessed area will be retained there because of surface tension, even when the distal end of the connector is vertically oriented. Thus, the droplet will act as a bridge between the connector pin and the outer body, creating a complete electrolytic cell. When alternating current is supplied, metal at both electrodes of the cell will dissolve at a relatively rapid rate.
Because of the rapid corrosion of connector pins, technicians must frequently inspect the connectors and replace them when necessary. If not replaced in time, the connectors will fail completely, sometimes bringing an entire transmission system to a halt. The time spent inspecting and repairing systems as a result of faulty connectors, as well as the expense of producing and maintaining a large inventory of replacement connectors, represents an undue burden to all concerned, including the consumer.
It would be highly advantageous, therefore, to remedy the foregoing and other deficiencies inherent in the prior art.
Accordingly, it is an object of the present invention to provide an improved connector for securing a coaxial cable to a selected device.
Another object of the invention is the provision of means for retarding the corrosion of the central conductor pin of a coaxial cable connector.
And another object of the invention is to provide an insulator configured to prevent liquid from bridging the pin and outer body of a coaxial cable connector.
Still another object of this invention is the provision of a coaxial cable connector with an improved dielectric having a domed upper surface for preventing surface tension from retaining a water droplet between the pin and outer body of the connector, even when the distal end of the connector is vertically oriented.
Yet another object of the invention is to provide an insulator sheath for surrounding the central conductor pin of a coaxial connector to prevent liquid from bridging the pin and the outer body of the connector, even when the distal end of the body is submerged in liquid.
Yet still another object of the immediate invention is the provision of an improved coaxial cable connector configured to be received in an entry port of standard configuration and dimensions, with no need for modifications to the entry port.
And a further object of the invention is to provide new and novel insulators for coaxial cable connectors using conventional and readily available materials.
Still a further object of the invention is the provision of a new and novel coaxial cable connectors which are readily fabricated with pre-existing technology and machinery.
And still another object of the invention is to provide improved coaxial cable connectors which are conveniently field installed using traditional skills and tools.
Yet still a further object of the invention is the provision of a coaxial cable connector, according to the foregoing, which is relatively inexpensive and maintenance free.